Atraumatic Knee Pain in a Middle Aged Tennis Player

Dr Christopher Vertullo MBBS FRACS Orth

A 62-year-old tennis player presents to you complaining of an atraumatic onset of knee pain over the last few weeks. The pain is associated with a clicking sensation at the front of the knee and is worse after playing. She has never had this type of problem before and is concerned about a meniscal tear.

When you examine her knee, you note that she has a BMI of 31, a full range of active knee motion, no effusion, some wasting of her quads and some patellofemoral crepitus. The medial side of her knee is not tender.

Your next management step should be:

A To arrange an MRI and urgent review

B To reassure that no investigations are needed at this stage as the most likely diagnosis is Patellofemoral Osteoarthritis, and that quadriceps strengthening with her physiotherapist is all that is required. 

C To suggest to stop playing tennis and start some NSAID.

D To arrange an MRI and urgent orthopaedic surgical review

The correct answer is obviously B. An atraumatic onset of knee pain in a middle-aged patient will be degenerative change, in this case of the Patellofemoral joint. The initial management should be to avoid investigations at this stage, lose some weight, strengthen the quadriceps with her physio and consider NSAID prior to playing if no contraindication.

The patient then returns 6 weeks later, the pain is much better, but she wants to get an MRI to "see what is happening". 

Should you order an MRI ?

The answer is "not really", as a plain radiograph, particularly looking at the Patellofemoral joint is much more helpful as the initial test. If you initial diagnosis is incorrect, and she has a meniscal tear, arthroscopy will not be indicated, unless her knee is locked or she has a repairable meniscal root tear. The place for MRI in these situations is rather limited, and only when non-operative management has failed or the diagnosis is uncertain from the history and examination. Finally, reassurance that it is safe to continue exercising is vital as it helps the patient lose weight. Patellofeomoral pain really responds to weight loss dramatically.

Which Investigation for the Painful Knee ?

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Dr Christopher Vertullo MBBS FRACS

It is always difficult knowing which investigation to order when a patient presents with a painful knee. Often the most expensive test is not the best, and in many situations some radiological modalities have no place at all. A 70-year-old male patient presents to you with increasing right medial knee pain and aching. It had an atraumatic onset, and is worse with activity.  He had pain which was 1-3 / 10 previously , but since helping his daughter move house 3 weeks ago it has become much worse, and is interfering with his sleep. You examine him and notice he walks with a limp, has a reduced range of motion to 5- 100 degrees with no effusion. His hip is not stiff to rotation and he has a good distal vascular perfusion to his feet.  He then asks for an MRI, “like all the footballers get”.   

Investigation of atraumatic  onset knee pain should always start with a plain radiograph. A series of four XRs, is the Gold Standard. These include an Erect Antero-Posterior (AP) Radiograph, a Lateral, a Patellofemoral view and an erect flexion AP, known as a Rosenberg. Oblique X-Rays are rarely useful. 

What about the MRI ? Well in these situations, middle-aged or older patients with atraumatic onset of their pain, MRI is only a secondary investigation as the diagnosis is an exacerbation of osteoarthritis and degeneration . In fact, often the XR is all that is needed. The only reason to get an MRI is if the XR shows very little osteoarthritis and the patient fails to settle with a few weeks of rest. In these situations, a stress fracture can present with a similar history but fails to settle with rest. 

The Australian Knee Society recently combined with the Australian MusculoSkeletal Imaging Group to produce a position statement for the investigation of the degenerative knee. It is a handy reference for all musculoskeletal primary care practitioners.